这个词是什么意思？
The age of the conceptus, beginning from the time of FERTILIZATION. In clinical obstetrics, the gestational age is often estimated from the onset of the last MENSTRUATION which is about 2 weeks before OVULATION and fertilization. It is also estimated to begin from fertilization, estrus, coitus, or artificial insemination.
中文名称索引；定义为 MeSH 英文原文，尚未逐条译审。MESH:D005865 · MeSH 2026。
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